Canadian Inuit and the Arctic Dilemma
Human exposure to anthropogenic contaminants is now a well-known phenomenon in the Canadian Arctic. Early work conducted on Baffi n Island and in Nunavik has demonstrated that because of their traditional dietary habits (Dewailly et al., 1989; Dewailly et al., 1993; Kinloch et al., 1992; Muckle et al., 2001), Inuit populations are exposed to environmental contaminants by eating their traditional foods, and their infants are exposed through transplacental and breast milk transmission from the
... it mother (Figures 1 and 2) . Th e two main groups of contaminants that may aff ect human health are the heavy metals (e.g., mercury), and the persistent organic pollutants (POPs) (e.g., polychlorinated biphenyls [PCBs], DDT, and other pesticides). POPs form a class of persistent organic pollutants including polychlorinated dibenzo p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), PCBs, and various chlorinated pesticides or industrial products. A new generation of POPs has recently been found in the Arctic food chain. Th ese new chemicals include the brominated fl ame retardants, in particular polybrominated diphenyl ethers (PBDEs), and the perfl uorinated alkane compounds (PFAs). Th ese new POPs were fi rst measured in freshwater and marine organisms, then subsequently in Inuit foods. Furthermore, there is also concern because the levels of all these substances are increasing. Th e high lipophilicity and resistance to biodegradation of POPs allow their bioconcentration and prolonged storage in the fatty tissues of animals. As the Inuit diet is comprised of large amounts of tissues from marine mammals, fi sh, and terrestrial wild game, the Inuits are more exposed to food chain contaminants than human populations living in temperate regions. EPIDEMIOLOGIC STUDIES Various studies have been conducted in Nunavik (northern Québec) over the past decade on the characterization of exposure of Inuit populations. Moreover, biological markers were also validated to detect and evaluate early biological changes that could result in altered immune and nervous system function, oxidative stress, and in subsequent chronic diseases. Most of these studies have focused on maternal and cord-blood analyses because of the susceptibility of the fetus to contaminant exposures. In Nunavik, an epidemiological study conducted from 1989-1991 investigated whether organochlorine exposure was associated with the incidence of infectious diseases and immune dysfunction in Inuit infants (Dewailly et al., 2000b). Th e number of infectious-disease episodes during the fi rst year of life of 98 breast-fed and 73 bottle-fed infants was determined. Concentrations of POPs were measured in early breast-milk samples and used as surrogates for the prenatal exposure levels. Otitis media (middle-ear infection) was the most frequent disease, with 80 percent of breast-fed and 81 percent of bottle-fed infants experiencing at least one episode during the fi rst year of life. However, the risk of otitis media was signifi cantly increased with a history of prenatal exposure to dichlorodiphenyldichloroethylene (DDE), hexachlorobenzene (HCB), and dieldrin. Th e relative risk for the 4-to 7-month-old infants most exposed to DDE was twice that Figure 1. Inuit capturing a seal. Figure 2. Inuit boy eating traditional diet.